The present invention is an improvement upon the vaporizer disclosed in my earlier German Pat. No. DE-PS 36 26 933 C2 issued May 5, 1989, which corresponds to my aforementioned application U.S. Ser. No. 07/ 311,839. In that vaporizer, the fuel and water, for generating the vapor mixture, are fed continuously. When it is necessary to operate the combustor at a low thermal capacity, this continuous feeding leads to problems because then only small amounts of fuel and water are fed to the vaporizer, and these amounts are hard to properly ration or deliver. Further, when the mixture composition must be rapidly changed, one can only partially achieve proper matching of the components going into the mixture.
U.S. Pat. No. 1,719,397, EDWARDS, issued July 2, 1929, discloses drawing liquid fuel through a Venturi-type constriction f into a steam-carrying tube. However, one cannot generate a qualitatively constant fuel vapor/water vapor mixture in that manner.